Auxiliary elevator control apparatus



Aug. 5, 1952 R. w. RAINE EI AL AUXILIARY ELEvAToR CONTROL APPARATUS Filed April 18, 1949 3mm/vbo ATTORNEY,

Patented Aug. 5, 1952 OFFICE AUXILIARY ELEvA'roa CONTROL APPARATUS Russell W.v Raine, Coral Gables, and Philip G. Sutker, Miami Beach, Fla.

Application April 18, 1949, Serial No. 88,064

This invention relates to a new and improved application of auxiliary power forl an electricallydriven elevator and to the automatic control for the operation thereof.

In buildings having electrically-driven elevator service, it is customary to receive the electrical supply from the main line of the power company entering the building where the elevator is located, such as is furnished for a whole city or community by public utility company, privately owned diesel electric plant or other generating sources.

It frequently happens that the source of electrical supplyfrom the main line will fail due to emergencies arising in the power plant or along the distribution system. Again in the casevof an emergency occurring in the building, such as in the case of fire, it is customary for the nre department or other authorities to cut the entire buildingoff from the main line source of electrical supply.

Any failure or disconnecting from the building of the main line source of electrical supply into the elevator equipment operating the elevator or elevatorsl seriously disrupts the service rendered by the elevator and in the case of emergency such as -re and the like a disruption of the elevator service in a building immediately bccomes a hazard to the occupants of that building. v

Accordingly, an object of this invention is to provide automatic controls for an auxiliary power unitwhich will automatically supply current to an electrically-driven elevatorthat comes into operation upon discontinuance for any reason of the main line source of elecrical supply.

Heretofore auxiliary electrical power 'units for elevators have been provided that operate on batteries which in turn drive or supply power to a direct current electric elevator equipment, as specifically set forth in the patent to Davis et al., No. 1,399,605. Auxiliary units such as these have many drawbacks. To'mention only a few they will serve to operate only on elevator equipment running on direct current, the auxiliary unit must be manually operated and set in to contact with the equipment by an attendant, they are neither designed or intended to operate with the three-phase electric elevator equipment inA present-day use, are not sensi' tive to failure of any phase of the currentl but only to the 'complete failurel of the current, and lastly the batteries require constant charging, maintenance and replacement.

Accordingly, it is a further object of this in- 11` claims. (o1. 1714-97) vention to provide a new and improved auxiliary power unit application that overcomes these objections and is automatically controlled for 3 phase electric elevator equipment, the power unit of-which consists of an electrical generator driven by an internal combustion engine that supplies a three-phase electric current to the elevator equipment.

Another object ofY this invention is to provide a fully automatic control for the auxiliary power generating unitthat will start the internal combustion engine and drive the auxiliary generator upon failure for any reason of th entire main line current supply into the elevator equipment or upon failure .of any phase thereof,

Afurther object of this invention is to provide a control for the auxiliary power unit that automatically disconnects the elevator equipment entirely from the main line supply and connects the elevator equipment to the auxiliary generator upon failure of the entiremain line current or anyphase thereof.

Another object of this invention is to provide a control that upon full three-phase energization of the main line source of supply will automatically shut down the internal combustion engine driving the auxiliary generator, disconnect the elevator equipment from the generator and again connect the elevator equipment to the fully operating main line source of electrical supply.

A further object of this invention is to provide av control for activating and de-activating an auxiliary power unit for a three-phase elevator equipment that is fully automatic and is prevented from hunting Yet a further object of this invention is to provide a timed delay in the automatic control of the auxiliary power unit that will function upon the reactivation of the main power supply.

Again it is recognized that in three-phase power generation of both the main line and auxiliary power supplyY and that in switching from one supply to the other there may occur a reversalof thev phases to the elevator equipment, thus doing considerable damage to the mechanism of the elevator equipment and in some instances even preventing operation of the elevator equipment. Accordingly, it is a further object of this invention to provide a phase reversal control in the system that will insure a delivery of the proper' phase rotation of current to the elevator equipment at all times and under all conditions, whether thev source of electrical supply to the elevator equipment be from the main line or the auxiliary power unit.

operated by the timer equipment during the com-- plete cycle of operation of the system embodied by our invention.

Referring lnow to a detailed discussion of the' drawings, the numeral 5 designates generally a three-phase alternating current motor for driving an elevator or elevator equipment. `Connected t this motor are three lines designated generally by the numeral 6, and severally by the numerals 7, 8 and 9. Connected to the lines 7, 8 and 9 by means of a switch I0, which may be of any type desired such as a three-blade knife switch,-is a main line source of supply designated generally by the numeral II and customarily furnished by a city power plant, `public utility or the like.

The power `supply II is connected into the system by means of three lines designated generally as I2, I3 and I4.` The lines I2, I3 and I4 are connected to the lines 7, 8 and 9 by means of an electrically operated switch I5, shown in a closed position to the power line I I in Fig. 1.

Shunted across the lines 7, 8 and 9 are connectors I6, I7 and I8 which connect to a winding I9 of a torque motor or reverse phase relay, designated generally by the numeral 28. The center tap of the winding I9 is connected by the line I7 to a line 2l, which in turn is connected through the switch I to the line I4. One side of the primary winding I9 is connected by the line I6 to the line 9, which in turn is connected by means of the switch I5 to line I2 of the main line source of supply. The opposite side `of' the primary winding I9 of the reverse phase relay is connected by means of line I8 to line 22, which in turn is connected by means of the switch I5 to line I3 of the main line source of supply.

A phase reversing switch, designated generally by the numeral 23, is provided in series with lines 2| and 22 and connects these lines alternately with lines 7 and 8. The phase reversing switch 23 consists of a pair of solenoids or the equivalent 24 and 25 operating a bar 26,'in turn pivotally connected to blades 27, 28 and 29 of the switch proper. The blade 27 is also pivoted at 3U to a connector line 3l making contact with line 7. Blade 29 is also pivotally connected to a contact 32 also makingconnection with line'7. Whereas blade26 is pivotally connected at 33 to a conhector going to line 8. There is a dead contact 34 with which Vblade 29 makes contact in one position, vblades 27 and 28 at the same time making connection with contacts k35 and 36 .which are respectivelyconnected to lines 22 and 2|. Upon reversal of the phase relay switch, the blades 27, 28v and 29 take the position shown byl dotted lines. Blade 27 makes contact with a dead contact 34', blades 28 and 29 making connection with contacts 35 and 3G respectively..

The coil 24 is connected at 40 to line 22 by means of a connector 4I and to a contact 42 of the reverse phase relay 26 by means of line 43. The coil 25 is also universallyconnected to the line 22 by means of connector 45 through a line 44 in one direction, the armature 49 will be pulled in one direction and a contact 5I will close against either contact 42 or 45, depending upon the direction of phase rotation of the current passing through the winding I9. If the current is in a clockwise direction through the lines I6, I7 and I8, the armature 49 will be pulled to the dotted line position shown and will actuate the coil 24, which in. turn will operate the phase reversing switch 23 into the position as shown. Upon reversal of the phaserotation of the current through the linesl I6, I7 and I8, the contact 5I will be closed with the contact 45, thus actuating the coil 25 and de-energizing the coil 24. This will throw the phase reversing switch 23 into the position shown by the dotted lines and the current owing from 1ines.2I and 22 into the lines 7 vand 8 will be reversed.

:Turning now to a detailed description of the electrically actuated switch I5, of any conventional type, the coil of which is designated by the numeral 52, actuates the armature 52', which in turn is pivotally connected to blades 53, 54 and 55 pivoted about points 55, 57 and 58. There is a secondvseries of blades connected rigidly to blades 53, 54 and 55, designated by the numerals 59, 460 and 6I. A spring 62'can be connected tok blade 6I. to cause the switch I5 to normally re. main in a closed position, as shown in Fig. l, which connects the elevator equipment to the main line source of supply Il or this device may begravity-operated being in a normal down position without mechanical means of holding same in this position. Y Upon energization ofthe coil 52 the switch I5 will take the position shown by dotted lines, opening the blades 53, 54 and 55 from the lines I4, I3 and I 2, respectively, and closing the blades 59, 66 and 6I against contacts 62, 63anvd`64. Contacts 62, 63 and 64 are connected to an alternating current three-phase generator 65 by means of lines 66, 6 7 and 68. l l

Turning now for a moment to a general description of phase failure relays designated generally by the numeral 70, lines 7|, 72 and73 are connected, respectively, to lines l2, I3 and I4 of the main line source-of supply II. Lines 7I, 72 and 73 are connected in Y withA coils 74, 75 and 76 relay 74 being connected on one side to linev 7| and onthe other side to line 77,v which in turn is connected to both relays 75 and 76; and relay 75 is .connected on one side to line 72 and tothe other side by means of line 77 to relays 74 and 76; relay 76 is connected on4 oneside to line 73 and lon .the otherY side by means of line 77 to relays ..74and 75.v

Relay'74 is provided with an armature 79 that acts as a switch blade` and lmakes contact with contact 3| connecting line 98 to line 93; relay 7 5 -is provided with an armature vrthat acts as switch blade 83-which connectsv thecontact 85.- Thisl connectsline 93 to line 92.v Relay 76 is provided with an armature that acts as switch blade 87Y which makes contact with contact 89 connecting line`92 to line 95. l

y The electrical contact 8| is connected to` switch blade 83 by means of a line E23 and electrical con tact 85 is connected to switch blade el by means of line 92. Electrical contact Se is connected to a battery 94 by means of a line 95. Battery 55| in turn is connected to a relay 55 by means oi line 91 and relay 95 in turn is connected to elec-y trical contact blade 'I9 by means ci line Turning for a moment to the operation ci phase failure relays, it will be above that the relays lli, 'E5 and are connected in Y across lines I2, I3 and I of the main line source of electrical supply il. The electrical switches 1S, 822 and Si operated by relays 14, 'I5 and l5, respectively, are connected in series with each other, with the battery ai and with relay 96. Upon failure of vthe main line source of current I or any one phase thereof, the relays 14%, I5 and l', or any one relay, will become cle-energized and the switches 55 and 5l or any switch in which the relay has become energized will open. The deenergization ci any of the relays 1d, 'i5 and 'le will open the circuit through relay 55, thus de-energizing thesame.

Turning now to a detailed description ofthe switch, designated generally by the numeral |05 operated by the relay the numeral |il| designates an armature of relay 95. To the armature I||`| are rigidly connected arms |52 and |53. Arm |02 closes contacts |94 and Iill and to contact |04 is connected lineIilE, which in turn is connected into line el at |51 and contact IE5 is ecnn nected by means oi" lineISS to a contact |55. Contacts III are dead. Switch lili] is gravity operated and remains in the position shown in solid lines only when the relay Qd is energized. When relay 95 is cle-energized, armature |5I drops downward by gravity and arms It and |53 take the position shown by dotted lines. When relay 95 is de-energized, arm |52 connects contacts |I| and II2 and arm |23 connects contacts II3-and IIlI. Contact III is connected to line |06 and contact II2 is connected to contact |I5 by means of line H5. Contacts IIS and ||4 are connected by means of lines I I'I to starting equip-v ment' of an internal combustion engine (not shown). The internal combustion engine in turn drives generator 55.

Turning now to a detailed description of the timer designated generally by the numeral I2l, |2I is a direct current motor connected by means of line |22 to battery 94 and by means of line |25 and 'contacts |24 and |25 to switch arms |25 and |21 to lines ||6 and |58, respectively. Connected to the armature of motor IZI is a shaft drive |28 and securely mounted cn the drive shaft |28 are arms |26 and |21, as well as arms |29 and |3|). It is here pointed out that suitable means of any known type may be provided for adjusting or varying the cycle ci rotation of the motor |2I.

The switch arm |29 cooperates with contacts |3| and |32, which in turn are connected by means of lines |33 in series with the coil 52 and one phase or side of the alternatingr current threephase generator 65; and switch arm |35 cooperates with contacts |34 and |35, which in turn are connected by lines |35 to the internal combustion engine stop which is of conventional design and accordingly not shown in this schematic drawing. n

Turning next to a detailed description of the operation of the schematic diagram shown in Fig. 2 of the operation of the timer |2I andthe arms |25, |21, |29 and |36, the numeral |40 desigi5, respectively.

seen from the 6, nates schematically the position of arms |25 and |29 and represents the closing of the contacts |I5 and |24, and |3| and |32, respectively, by arms |25 and |25. vThis represents the position ofthe timer motory and the contact arms in respect to their Contact points during the normal operation of the elevator equipment 5 from the main line source of electrical energy |I. It-will be seen from a study of Figs. 1 and 2 that the timer motor |2|` isnow in a position ready to start operation, that lines and |22 close the motor I2I through the battery 94 and contacts I II and II2, but the relay 95 being energized the contacts I I and II2 are open and therefore the motor |2I is in a period of rest. Contacts |3| and |32 being connected in series through the coil 52 and generator 55, this circuit is fully closed. With the emergency generator being shut down during normal operation of the main line source of current II, the coil 52 will be deenergized and the switch I5 will remain in its normal operating position shown in solid lines.

The second position of the timer motor and switches is designated generally by the numeral ilI in which arms |21 and |29 are in a position to close contactV IilS, to contact |25, andcontact |3| to contact |32, respectively. It will be seen from a study of the drawings that this represents the position ci the timer shortly after there has been a failure of the main line source of supply or any one phase of the three-phase current and the relay 96 hasr been de-energized and the arms It and |03 have fallen by gravity into the dotted line positions closingv contacts I I I, H2, Ils, and Ild. It will beapparent that the operation of the timer is now in a position to start the internal combustion engine fromA lines l Il, which in turn drives the generator' 55. Upon the starting of the generator 55, the circuit to the coil 52 having been closed through line |33 by means of switch |29 closing contact IiI to contact |32, the coil 52 will be energized and will open the blades 53, 54 and 55 to open the circuit to lines I2, I3 and lil, and will close blades 59,

50 and 5| against contacts 62, 53 and 54. This ink turn will connect the elevator equipment 5 with the emergency generator and the elevator equipment may then be operated in its normal function from the emergency generator.

Moving now to an explanation of the control when the timer is in the position shown by the schematic diagram designated by the numeral |22, the motor I2I can only be operated through lines |08 and |55 and contacts IDS, |25, |24 and |25 and the battery 54; thus with the arm |02 being in an up position closing contacts |64 and |05 and with the relay 95 again energized. This situation will occur upon the reactivation of the main line source of supply II with the relays 24, E5 and 'IG again all being closed. We now have a time delay to prevent hunting of the auxiliary motor and control apparatus in case the auxiliary supply comes on only momentarily and then goes oif again, thus preventing the continuous starting and stopping oi the internal combustion engine, At position |42 only contacts |09 and |25 are closed by arm I2?, contacts IIE, |24, |3|, |32 and |34 and |35 being open at this position of operation and remaining open for tlimed period as controlled by the timer motor After a predetermined time interval, the motor |2| will rotate or move arms |21 and |3|! to the positions shown in the schematic diagram designated generally as |43, and contacts |05 and |25 and |34 and |35 will be the only contacts closed. This position operates the stopping apparatus for the internal combustion engine connected to lines |36; after which with the timer motor still operating until its cycle has been completed, the position of the arms shown by the schematic diagram |40 is again reached, and the motor |2I is stopped thereon ready for the next cycle of operation.

To review very briefly the general operation of the electrically operated auxiliary elevator control apparatus for elevator equipment, the phase reversing switch designated generally by the numeral 23 operated by the torque motor or reverse phase relay will keep the phase rotation of the current going to the elevator equipment in proper phase relation regardless of Whether the motor is operating from a main line source of current or an emergency generator 65. The relay 'l0 will set into operation the controls for starting and stopping the emergency generator 65 upon failure or reactivation of the main line source of current or any single phase thereof and the timer motor |2| activated by the electrically operated switch 96 will control the stopping and starting of the internal combustion engine which drives the emergency generator 65, and at the same time will prevent the control from hunting.

It is to be understood that the variations in switches, torque motor or reverse phase relays, phase reversing switches, timer controls, engine starting and stopping devices and the like may be resorted to without deviating from the spirit of our invention as cove ed by the following claims. l Y

We claim: n

1. An electrical auxiliary elevator control apparatus for electrical elevator operating equipment comprising an electric motor, means for operating an elevator driven by said motor, adapted to primarily be driven by a main line source of alternating current power, an auxiliary source of power for operating said electrical equipment comprising a three-phase alternating current generator, and an internal combustion engine for driving said generator, and control means to automatically alternately connect said elevator equipment to the main line source of power and to the auxiliary source of power, said control means causing the internal combustion engine to operate in timed relation to the function of a main line source of power.

2. An electrical auxiliary elevator control ap-l paratus for electrical elevator operating equipment comprising a main line source of threephase alternating current power for operating the elevator equipment, an auxiliary source of three-phase alternating current power for operating the elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, control means .to automatically alternately connect said elevator equipment to the main line source of power and to the auxiliary source of power and a phase controlling means connected to the elevator equipment for controlling the current phase rotation to the elevator equipment from both the main and auxiliary sources of power.

3. An electrical auxiliary elevator control apparatus for electrical elevator operating equipment comprising a main line source of threephase alternating current power for operating the elevator equipment, an auxiliary source of three-phase alternating current power for operating the elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, control means to automatically alternately connect said elevator equipment to the main line source of power and to the auxiliary source of power and a phase controlling means connected to said elevator equipment for controlling the current phase rotation to said elevator equipment from both the main and auxiliary sources of power, said phase controlling means comprising a reverse phase relay switch connected to the elevator equipment. an electrically operated phase reversing switch having a pair of coils or solenoids connected in series with two of the lines leading to said elevator equipment, a pair of switch contacts connected to said reverse phase relay, each of said contacts being connected in series with one of the said coils or solenoids of the phase reversing switch.

4. An auxiliary elevator control vapparatus for electrical elevator operating equipment, comprising a main line source of three-phase alternating current power for operating the elevator equipment, an auxiliary source or" three-phase alternating current power for operating the elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, control ternately connect said elevator equipment to the main line source of power and to the auxiliary source of power, said control means comprising electrically operated switches actuated on phase failure and connected to the main line source of power and means controlled by said electrically operated switches for starting and stopping said auxiliary generator and for alternately disconnecting and connecting said electrical elevator equipment from said main line source of power to the auxiliary source of power, and a phase controlling means connected to said elevator equipment for controlling the current phase rotationv to said elevator equipment from both the main line and auxiliary sources of power.

5. An electrical auxiliary elevator control apparatus for electrical elevator operating equipment comprising a main line source of threephase alternating current power vfor operating said elevator equipment, an auxiliary source of three-phase alternating current power for operating said elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, control means to automatically alternately connect said elevator equipment to the main line source of power and to the auxiliary source of power, said control means comprising a plurality of phase switches, said relays being connected in Y across the main line source of power and the switches being connected in series, whereby failure of any one phase of the main line source of supply will open the circuit through said switches. means controlled by said relays for starting and stopping said auxiliary generator and for alternately disconnecting and connecting said elevator equipment from said main line source of power to the auxiliary source of power, and a phase controlling means connected to said elevator equipment for controlling the current phase rotation of said elevator equipment from both the main and auxiliary sources of power.

6. An electrical auxiliary elevator control apparatus for electrical elevator operating equipelevator equipment, phase alternating current power for operating means to automatically al the elevator equipment, said auxiliary `source of power comprising va three-'phase alternating current generator, control means to automatically alternately connect said elevator equipment to the main line source of power and to the auxiliary source of power, said control means comprising `a plurality of electrically operated phase failure relay switches, said relays being connected in Y across the mainline source of power and the switches being connected in series,

whereby failure of any one phase of the main line source of supply will open a circuit through `said switches, means controlled by said relays for starting land stopping said auxiliary `generator and for alternately disconnecting and connecting said elevator vequipment from A'said main line source of power to the auxiliary Vvsource of power in timed relation to the function of the main line source of power, "and a phase controlling means connected to said elevator equipment for controlling the current phase rotation to the elevator equipment from both the main and auxiliary sources of power.

7. An electrical auxiliary elevator control apparatus for electrical elevator operating. equipment comprising an electric motor, means for operating an elevator driven by said motor, a main line source of power for operating said electric motor, an auxiliary source of power for operating said elevator equipment comprising a three-phase alternating current generator, and an internal combustion engine for d riving said generator, an electrically operated phase failure relay switch connected to the main line source of power and means controlled by said relay for starting and stoppingthe internal combustion engine in timed relation to the function of the said main line source of power.

8. An electrical auxiliary elevator control apparatus for electrical elevator operating equipment comprising an electric motor, means for operating an elevator driven by said motor, a main line source of three-phase alternating current power for operating said electric motor, an auxiliary source of three-phase alternating current power for operating said electric motor, said auxiliary source of power comprising a threephase alternating current generator, an electrically operated two-way switch adapted to alternately connect said electric motor to said main line and auxiliary source of power, a phase failure relay switch connected to said main line source of power, an electrically operated relay actuated by said phase failure relay switch, said control operating the auxiliary generator in timed relation to the function of the main line source of power and the electrically operated two-way switch in timed relation to the function of the auxiliary power source generator.

9. An electrical auxiliary elevator control apparatus for electrical elevator operating equipment comprising a main line source of threephase alternating current power for operating said elevator equipment, an auxiliary source of three-phase alternating current power for operating the elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, an electrically operated two-way switch adaptedv to alternately connect said elevator operating equipment to said main line and to auxiliary sources of power, a phase failure relay switch connected to said main line source of power, an electrically operated relay actuated by said phase failure relay switch, said control operating the auxiliary generator in timed relation to the function of the main '-10 line 'source of power and the electrically operated two-way switch in timed relation to the "function of the auxiliary power source generator,

`said electrical control comprising an electrically operated switch connected' with said phase failure relays and a constant source of electrical energy, an electrically operated two-'way switch actuated by the last mentioned relay, a timer motor operated by `said electrically operated two-way switch and movable contacts operated by 'said motor for controlling the circuits to the electrically operated two-way switch, the auxiliary generator and the'elevator equipment itself in timed relation.

10. An electrical auxiliary elevator 'controlapparatus for electrical elevator operating equipment comprising a main line source of threephase alternating current power for operating said elevator equipment, an auxiliary source of three-phase alternating current power for operating said elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, an electrically operated two-way switch adapted to alternately connect said elevator equipment to said main line and auxiliary sources of power, a plurality of electrically actuated relay switches connected in Y to the main line source of power across the main line source of power, the switches of said relays being connected in series whereby the failure of any one phase of the main line source of supply will open the circuit of said switches, an electrically operated switch actuated by said phase failure relay switches, said control operr ating the auxiliary generator in timed relation to the function of the main line source of power and the electrically operated two-way switch in timed relation to the function of the auxiliary power source generator, said electrical control comprising an electrically operated switch connected in series with said phase failure relay switches and a constant source of electrical energy, a pair of electrically operated two-way switches actuated by said above mentioned relay, a timer motor operated by one of said two-way switches and movable contacts operated by said motor for controlling the circuits to the electrically operated two-way switch, the auxiliary generator and the elevator equipment itself in timed relation.

ll. An electrical auxiliary elevator control apparatus for electrical elevator operating equipment comprising a main line source of threephase alternating current power for operating said elevator equipment, an auxiliary source of three-phase alternating current power for operating the elevator equipment, said auxiliary source of power comprising a three-phase alternating current generator, an electrically operated two-way switch adapted to alternately connect said elevator equipment to said main line and to auxiliary sources of power, a plurality of electrically actuated relay switches connected in Y to the main line source of power across the main line source of power, the switches of said relays being connected in series whereby the failure of any one phase of the main line source of supply will open the circuit of said switches. an electrical control actuated by means of phase failure relay switches, said control operating the auxiliary generator 'm timed relation to the function of the main line source of power and to the electrically operated two-way switch in timed relation to the function of the auxiliary power source generator, said electrical control comprising an electrically operated switch connected and a constant source of electrical energy, an

electrically operated pair 0f` two-Way switches actuated by above-mentioned relay, a timer motor operated byrone of said two-way switches and movable controls operated by saidmotor for controlling the circuits to the electrically operated two-way switch, the auxiliary generator and the elevator equipment itself in timed relation, and a phase controlling means connected to said elevator equipment for controlling the current phase rotation to said elevator equipment. from both the main and auxiliary sources of power, said phase controlling means comprising a reverse phase relay switch connected to said elevator equipment, an electrically operated 'phase reversing switch having a pair of coils or solenoids connected in series with two of the lines leading to said elevator equipment, a pair of switch contacts connected to said reverse phase f relay, each of said contacts being connected in series with one of the said coils or solenoids.- -v

' RUSSELL W. RAINE. PHILIP G. SUTKER.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,025,590 Rice May 7, 1912 1,182,265 Gale May 9, 1912 1,279,392 Martinetto Sept. 1, 1918 1,662,366 Cosgray Mar. 13, 1928 1,888,856 Fuller Nov. 22, 1932 2,003,036 Callahan May 28, 1935 2,427,678 Laging Sept. 23, 1947 2,451,976

Reagan et al. Oct. 19, 1948 

